A communication architecture compliant with WAVE (Wireless Access in Vehicular Environment) is defined in Non-Patent Literature 1. WAVE is a standard for communication between a vehicular communication terminal mounted in a vehicle (hereinafter referred to as an onboard terminal) and an onboard terminal mounted in a different vehicle or a communication terminal installed along a road (hereinafter referred to as a roadside unit).
According to Non-Patent Literature 1, two types of channels, namely, a control channel and a service channel, are used to perform communication between the onboard terminal and a service provider terminal such as a roadside unit. The service provider terminal is a communication terminal managed by a service provider that provides predetermined services.
The service channel is used to transmit and receive information for providing (and receiving) services. The control channel is used to distribute, for example, information (WSA (Wave Service Advertisement)) for initiating communication on the service channel between the onboard terminal and the service provider terminal. A plurality of frequencies are prepared for use on the service channel. The WSA includes service type information and channel information. The service type information indicates the type of service to be provided by a distributor of the WSA. The channel information is used to identify a service channel (i.e., frequency) that is used to provide the service.
The service provider terminal uses the control channel to successively broadcast a WSA for a service to be provided by the service provider terminal. If, for example, a response to the WSA is returned from an onboard terminal, the service provider terminal starts communicating with the onboard terminal by using the service channel.
Upon receipt of a WSA, the onboard terminal performs a process based on the service type information included in the WSA. More specifically, the onboard terminal references the service type information in the received WSA to determine whether the type of service to be provided by a distributor of the WSA is available to the onboard terminal. If the type of service is available to the onboard terminal, the onboard terminal opens a service channel indicated by the received WSA. Opening a service channel is initiating communication with the distributor of the WSA by using a predetermined service channel. By contrast, if the type of service is unavailable to the onboard terminal, the onboard terminal does not open the service channel.